Bidirectional iterative beam forming

ABSTRACT

Bidirectional iterative beam forming techniques are described. An apparatus may include a wireless device having an antenna control module operative to initiate beam formation operations using an iterative training scheme to form a pair of communications channels for a wireless network, the antenna control module to communicate training signals and feedback information with a peer device via the transceiver and phased antenna array using partially or fully formed high rate channels, and iteratively determine antenna-array weight vectors for a directional transmit beam pattern for the phased antenna array using feedback information from the peer device. Other embodiments are described and claimed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of, claims benefit of, and priorityto, U.S. patent application Ser. No. 12/262,904, filed Oct. 31, 2008,entitled “BIDIRECTIONAL ITERATIVE BEAM FORMING”, and U.S. patentapplication Ser. No. 12/939,417, filed Nov. 4, 2010, entitled“BIDIRECTIONAL ITERATIVE BEAM FORMING”, both of which are incorporatedherein by reference in their entirety.

BACKGROUND

Wireless communication systems communicate information over a sharedwireless communication medium such as one or more portions of theradio-frequency (RF) spectrum. Recent innovations in Millimeter-Wave(mmWave) communications operating at the 60 Gigahertz (GHz) frequencyband promises several Gigabits-per-second (Gbps) throughput within shortranges of approximately 10 meters. Because of the large signalattenuation and limited transmission power, many 60 GHz devices willrely on antenna arrays with high directivity gain to achieve the 10meter coverage. These devices use techniques to steer a “beam” from atransmitter antenna array around obstacles to find the best path to areceiver antenna array, thereby directing much of the antenna gaintowards the receiver antenna array. Techniques to discover and directenergy between antenna arrays of peer devices is typically referred toas “beam forming” or “beam steering” or “beam searching.” Beam forminggenerally attempts to steer an antenna beam at a transmitter while atthe same time focusing a receiver antenna in the direction of incomingpower from the transmitter. Conventional beam forming protocols,however, typically take a significant amount of training time before afinal high-speed communication channel is established between peerdevices. Consequently, techniques designed to reduce overhead associatedwith training time are desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one embodiment of a communications system.

FIG. 2 illustrates one embodiment of a wireless network.

FIG. 3 illustrates one embodiment of a phased antenna array.

FIG. 4 illustrates one embodiment of a state diagram.

FIG. 5 illustrates one embodiment of an iterative training scheme.

FIG. 6A illustrates one embodiment of a first message flow.

FIG. 6B illustrates one embodiment of a second message flow.

FIG. 7 illustrates one embodiment of a graph for beam forming gain.

FIG. 8 illustrates one embodiment of a third message flow.

FIG. 9 illustrates one embodiment of a phased antenna array.

FIG. 10 illustrates one embodiment of a logic flow.

FIG. 11 illustrates one embodiment of an article of manufacture.

DETAILED DESCRIPTION

Various embodiments may be generally directed to bidirectional iterativebeam forming techniques for wireless communication systems. Someembodiments may be particularly directed to an enhanced bidirectionalbeam forming protocol designed to concurrently generate bidirectionalcommunication channels between two or more wireless devices over awireless network, such as a 60 Ghz mmWave wireless video area network(WVAN) or wireless personal area network (WPAN), for example. Suchnetworks are sometimes referred to as “piconets” due to their limitedtransmission ranges and participating devices. The enhancedbidirectional beam forming protocol generates additional antenna gainfor directional antenna transmissions, thereby allowing training andfeedback information to be communicated at a higher data rate, resultingin reduced training time and overhead in setting up bidirectionalcommunication channels between two wireless devices.

Since the path loss at 60 GHz band is relatively high and the efficiencyof power amplifiers at 60 GHz is relatively low (e.g., CMOS poweramplifiers), directional transmission is needed to achieve the desiredcoverage area (e.g., approximately 10 meters). Namely, the antenna arraygain from both transmit and receive beam forming is needed to acquirethe signal-to-noise ratio (SNR) for reliable data communications. A beamforming protocol is typically used to find the optimal phase valueswhich maximize receiver SNR, received power or other criterion.

Currently, there are several different types of beam forming protocolsfor implementing directional transmission techniques. A firstdirectional transmission technique is referred to as a sector scan. Itforms several directional beams using predefined weights. Calibration isrequired, however, in order to form the requisite beams. Anothertechnique is based on singular value decomposition (SVD), whichtypically does not require calibration. SVD allows transmission overselected singular values by using the singular vectors for antennapatterns. In particular, the singular vector associated with the largestEigen value typically works well. It is worthy to note, however, that inorder to select the singular values and singular vectors, a devicetypically has to have an estimation of the entire MIMO channel, e.g.,the channel from every antenna element at the transmitter to everyantenna element at the receiver end. While the SVD technique providesimproved performance, it needs feedback information due to lack ofchannel reciprocity. This potentially introduces channel delay into theSVD directional transmission technique.

A piconet typically implements two general types of communicationstransmissions, each having different transmission envelopes orcharacteristics. For example, a first type of transmission may be adirectional transmission and a second type of transmission may be anomni-directional transmission. The different types of transmissions mayoccur at different transmission rates. For example, directionaltransmissions may be performed using a higher rate channel, and thesecond type of transmission may be performed using a lower rate channel.In a WirelessHD network, for example, the directional transmissions maybe performed using a high rate physical (HRP) channel, and the secondtype of transmission may be performed using a low rate physical (LRP)channel. The HRP channel may achieve a higher rate than the LRP channel,in part, through the utilization of larger amounts of bandwidth.

Since the location of a pair of devices is unknown duringinitialization, conventional techniques typically utilize a combinationof LRP channels and HRP channels for beam forming operations. Forexample, one conventional technique utilizes a beam forming protocol forphased array antennas that is based on an iterative training scheme. Inone embodiment, for example, the iterative trainings scheme may comprisea power iteration scheme. This beam forming protocol designed for oneway high rate data transmissions over a HRP channel, where the reverselink suffers from low rate data transmissions over a LRP channel.Feedback information for the iterative search process is transmittedover the LRP channel, which dramatically slows down beam formingoperations. This may be acceptable for applications where high rate datatransmissions are needed in only one direction, such as for videotraffic from a media source to a media sink. For applications where highrate data communications are needed in both directions, such as forcomputing centric applications, however, this introduces unwarranteddelay in beam forming operations.

To solve these and other problems, various embodiments implement anenhanced bidirectional beam forming protocol to perform bidirectionalbeam forming operations to reduce training overhead and link latencyduring beam forming operations. Some embodiments delay feedbackinformation until two-way transmit (or receive) beam forming weights aretrained, and then send the feedback over a beam formed link with ahigher rate (e.g., HRP channel). This may reduce or eliminate the needto use a LRP channel for beam forming operations. Additionally oralternatively, some embodiments interleave transmit and receive beamforming operations to allow use of partially trained links tocommunicate feedback information at a higher data rate. This reduces theneed to use an LRP channel during beam forming operations.

In one embodiment, for example, a wireless device may include a phasedantenna array communicatively coupled to a transceiver. The wirelessdevice may further include an antenna control module communicativelycoupled to the transceiver and the phased antenna array. The antennacontrol module may be arranged to perform beam formation operationsusing an iterative training scheme to form a pair of communicationschannels between the wireless device and a peer device. For example, theantenna control module may be arranged to communicate training signalsand feedback information with the peer device via the transceiver andphased antenna array. The information is communicated using almostexclusively high rate channels, or through partial use of low ratechannels to bootstrap setup of the high rate channels. This reducestraining time for the devices. The antenna control module iterativelydetermines antenna-array weight vectors (AWVs) for a directionaltransmit beam pattern for the phased antenna array using feedbackinformation from the peer device. Once trained the wireless devices maybe used for high-speed bidirectional data communications.

Additionally or alternatively, the antenna control module of a wirelessdevice may initiate bidirectional beam formation operations using aniterative training scheme to form a pair of communications channels fora wireless network. The antenna control module may be arranged tointerleave transmit and receive beam forming operations for a firstwireless device and a second wireless device to allow feedbackinformation received by the first wireless device from the secondwireless device to be communicated over a higher data rate channel(e.g., HRP channel).

The wireless devices as described herein may coordinate operationsbetween each other. The coordination may involve the uni-directional orbi-directional exchange of information. In some embodiment, theinformation can be implemented as signals. For example, traininginformation may comprise training signals or sequences. Furtherembodiments, however, may alternatively employ data messages. The terms“training information” and “feedback information” are meant to includeboth signals and data messages, depending on a given implementation. Theembodiments are not limited in this context.

Embodiments of the enhanced bidirectional beam forming protocol provideseveral advantages over conventional beam forming techniques. Forexample, the enhanced bidirectional beam forming protocol trains bothdirections of the communications link, allowing for a more structuredprocess prior to a bidirectional operation that is more symmetric, suchas in a PC environment. This provides superior performance relative toconventional beam forming protocols that allows the receiver of the highrate transmission to answer (e.g., ACKs etc.) in a low rate dedicatedphysical layer (PHY) that may not require training of the reverse link.In another example, the enhanced bidirectional beam forming protocolexploits resources more efficiently. The feedback provided during eachiteration is based on partially trained antenna arrays. In yet anotherexample, an external listening device can identify transmissions fromboth ends of the link. This situation is beneficial when an independentstation wishes to assess the amount of interference it is going tosuffer from the regarded link. If only one side of the link does thetransmission, however, then the station has knowledge about interferenceonly about the forward link and not about the reverse link. These areonly a few examples of the advantages provided by the enhancedbidirectional beam forming protocol, and it may be appreciated that manyother advantages exist as well.

FIG. 1 illustrates a block diagram of one embodiment of a communicationssystem 100. In various embodiments, the communications system 100 maycomprise multiple nodes. A node generally may comprise any physical orlogical entity for communicating information in the communicationssystem 100 and may be implemented as hardware, software, or anycombination thereof, as desired for a given set of design parameters orperformance constraints. Although FIG. 1 may show a limited number ofnodes by way of example, it can be appreciated that more or less nodesmay be employed for a given implementation.

In various embodiments, the communications system 100 may comprise, orform part of a wired communications system, a wireless communicationssystem, or a combination of both. For example, the communications system100 may include one or more nodes arranged to communicate informationover one or more types of wired communication links. Examples of a wiredcommunication link, may include, without limitation, a wire, cable, bus,printed circuit board (PCB), Ethernet connection, peer-to-peer (P2P)connection, backplane, switch fabric, semiconductor material,twisted-pair wire, co-axial cable, fiber optic connection, and so forth.The communications system 100 also may include one or more nodesarranged to communicate information over one or more types of wirelesscommunication links. Examples of a wireless communication link mayinclude, without limitation, a radio channel, infrared channel,radio-frequency (RF) channel, Wireless Fidelity (WiFi) channel, aportion of the RF spectrum, and/or one or more licensed or license-freefrequency bands.

The communications system 100 may communicate information in accordancewith one or more standards as promulgated by a standards organization.In one embodiment, for example, various devices comprising part of thecommunications system 100 may be arranged to operate in accordance withone or more of the WirelessHD™ specifications, standards or variants,such as the WirelessHD Specification, Revision 1.0d7, Dec. 1, 2007, andits progeny as promulgated by WirelessHD, LLC (collectively referred toas the “WirelessHD Specification”). The WirelessHD Specification definesa next generation wireless digital network interface for consumerelectronic products. Specifically, the WirelessHD Specification enableswireless connectivity for streaming high-definition content betweenvarious wireless devices, such as a source device and high-definitiondisplays. The WirelessHD Specification defines a wireless protocol thatenables the creation of a WVAN. In a current instantiation of theWirelessHD Specification, the MAC and PHY are defined to support thewireless delivery of uncompressed high definition audio and video atformats up to 1080 p at 60 Hertz (Hz) with 24 bit color at a range thatis typically at least 10 meters. In addition, the delivery of compressedaudio/visual (AV) streams and data is also supported at a similar range.An adaptation sub-layer enables network and service set up by supportingauthentication, advanced device and connection control.

Although some embodiments may be described with reference to theWirelessHD Specification by way of example, it may be appreciated thatthe techniques described herein may also be implemented for otherwireless standards as promulgated by other standards organizations aswell, such as the International Telecommunications Union (ITU), theInternational Organization for Standardization (ISO), the InternationalElectrotechnical Commission (IEC), the Institute of Electrical andElectronics Engineers (information IEEE), the Internet Engineering TaskForce (IETF), and so forth. In various embodiments, for example, thecommunications system 100 may communicate information according to oneor more IEEE 802.11 standards for wireless local area networks (WLANs)such as the information IEEE 802.11 standard (1999 Edition, InformationTechnology Telecommunications and Information Exchange BetweenSystems—Local and Metropolitan Area Networks—Specific Requirements, Part11: WLAN Medium Access Control (MAC) and Physical (PHY) LayerSpecifications), its progeny and supplements thereto (e.g., 802.11a, b,g/h, j, n, VHT SG, and variants); IEEE 802.15.3 and variants; IEEE802.16 standards for WMAN including the IEEE 802.16 standard such as802.16-2004, 802.16.2-2004, 802.16e-2005, 802.16f, and variants; nextgeneration WirelessHD (NGmS) progeny and variants; European ComputerManufacturers Association (ECMA) TG20 progeny and variants; and otherwireless networking standards. The embodiments are not limited in thiscontext.

The communications system 100 may communicate, manage, or processinformation in accordance with one or more protocols. A protocol maycomprise a set of predefined rules or instructions for managingcommunication among nodes. In various embodiments, for example, thecommunications system 100 may employ one or more protocols such as abeam forming protocol, medium access control (MAC) protocol, PhysicalLayer Convergence Protocol (PLCP), Simple Network Management Protocol(SNMP), Asynchronous Transfer Mode (ATM) protocol, Frame Relay protocol,Systems Network Architecture (SNA) protocol, Transport Control Protocol(TCP), Internet Protocol (IP), TCP/IP, X.25, Hypertext Transfer Protocol(HTTP), User Datagram Protocol (UDP), and so forth.

The communications system 100 also may be arranged to operate inaccordance with standards and/or protocols for media processing.Examples of media processing standards include, without limitation, theHigh Definition Television (HDTV) standards as defined by the ITURadiocommunication Sector (ITU-R), such as the Recommendation BT.709-5,Parameter Values for the HDTV Standards For Production and InternationalProgramme Exchange, published April 2002, the Digital Video BroadcastingTerrestrial (DVB-T) broadcasting standard, the ITU/IEC H.263 standard,Video Coding for Low Bitrate Communication, ITU-T RecommendationH.263v3, published November 2000 and/or the ITU/IEC H.264 standard,Video Coding for Very Low Bit Rate Communication, ITU-T RecommendationH.264, published May 2003, Motion Picture Experts Group (MPEG) standards(e.g., MPEG-1, MPEG-2, MPEG-4), and/or High performance radio Local AreaNetwork (HiperLAN) standards. Examples of media processing protocolsinclude, without limitation, Session Description Protocol (SDP), RealTime Streaming Protocol (RTSP), Real-time Transport Protocol (RTP),Synchronized Multimedia Integration Language (SMIL) protocol, and/orInternet Streaming Media Alliance (ISMA) protocol. The embodiments arenot limited in this context.

As shown in FIG. 1, the communications system 100 may comprise atransmitter node 102 coupled to a plurality of receiver nodes 104-1-n,where n may represent any positive integer value. In variousembodiments, the transmitter node 102 and the plurality of receivernodes 104-1-n may be implemented as various types of wireless devices.Examples of wireless devices may include, without limitation, an IEEE802.15.3 piconet controller (PNC), a controller, an IEEE 802.11 PrivateBasic Service Set (PBSS) Control Point (PCP), a coordinator, a station,a subscriber station, a base station, a wireless access point (AP), awireless client device, a wireless station (STA), a laptop computer,ultra-laptop computer, portable computer, personal computer (PC),notebook PC, handheld computer, personal digital assistant (PDA),cellular telephone, combination cellular telephone/PDA, smartphone,pager, messaging device, media player, digital music player, set-top box(STB), appliance, workstation, user terminal, mobile unit, consumerelectronics, television, digital television, high-definition television,television receiver, high-definition television receiver, and so forth.In such embodiments, the transmitter node 102 and the receiver nodes104-1-n may comprise one more wireless interfaces and/or components forwireless communication such as one or more transmitters, receivers,transceivers, chipsets, amplifiers, filters, control logic, networkinterface cards (NICs), antennas, antenna arrays, and so forth. Examplesof an antenna may include, without limitation, an internal antenna, anomni-directional antenna, a monopole antenna, a dipole antenna, an endfed antenna, a circularly polarized antenna, a micro-strip antenna, adiversity antenna, a dual antenna, an antenna array, and so forth. Inone embodiment, certain devices may include antenna arrays of multipleantennas to implement various adaptive antenna techniques and spatialdiversity techniques. Some embodiments for an enhanced bidirectionalbeam forming protocol are discussed in the context of using phasedantenna arrays. The enhanced bidirectional beam forming protocol may beused with any type of antenna having a need for feedback information,and the embodiments are not limited in this respect. For example, whilesome aspects of an enhanced bidirectional beam forming protocol aredesigned to enable a phased antenna array at both ends of the link, aswitched-sector antenna (e.g., an antenna with predefined few directionsthat can switch from one direction to another) may still use thisprotocol.

For purposes of illustration and not limitation, examples for anenhanced bidirectional beam forming protocol may be given with referenceto WirelessHD networks, protocols and devices. It may be appreciated,however, that an enhanced bidirectional beam forming protocol may beimplemented with other types of networks, protocols and devices. Forexample, an enhanced bidirectional beam forming protocol may beimplemented for a NGmS network, protocol or devices, and still fallwithin the intended scope of the embodiments. The embodiments are notlimited in this context.

In various embodiments, the transmitter node 102 and the receiver nodes104-1-n may comprise or form part of a wireless network 106. In oneembodiment, for example, the wireless network 106 may comprise a WVAN asdefined by the WirelessHD Specification. In the context of a WVAN, bothnodes 102, 104 may be implemented as WirelessHD compliant devices. In aWVAN, the transmitter node 102 may be communicatively coupled to one ormore receiver nodes 104-1-n. In accordance with the WirelessHDSpecification and nomenclature, one or both of the nodes 102, 104 may beimplemented as a coordinator or a station. A coordinator is normally,but not always, a device that is a sink for media information (e.g.,audio or video data). The coordinator typically includes a display, andin some cases a media storage device such as a personal video recorder(PVR), media server, or STB. A station may comprise a device that eitherhas media information that it can source or sink, potentially at thesame time.

Although some embodiments may be described with the wireless network 106implemented as a WVAN network for purposes of illustration, and notlimitation, it can be appreciated that the embodiments are not limitedin this context. For example, the wireless network 106 may comprise orbe implemented as various types of wireless networks and associatedprotocols suitable for a WPAN, a Wireless Local Area Network (WLAN), aWireless Metropolitan Area Network, a Wireless Wide Area Network (WWAN),a Broadband Wireless Access (BWA) network, a radio network, a televisionnetwork, a satellite network such as a direct broadcast satellite (DBS)network, and/or any other wireless communications network configured tooperate in accordance with the described embodiments.

As shown in the embodiment of FIG. 1, the transmitter node 102 may becoupled to receiver nodes 104-1-n by wireless communication links 108-n.A particular wireless communication link (e.g., wireless communicationlink 108-1) may be arranged to establish one or more common or dedicatedconnections between the transmitter node 102 and a particular receivernode (e.g., receiver node 104-1). In various embodiments, a particularwireless communication link (e.g., wireless communication link 108-1)may include multiple virtual channels, with each of the virtual channelscomprising a point-to-point logical connection from the transmitter node102 to a particular receiver node (e.g., receiver node 104-1). Invarious implementations, multiple virtual channels may share a physicallink, with each virtual channel comprising dedicated resources orbandwidth of the physical link.

In various embodiments, the nodes 102, 104 may communicate using aphysical layer component (PHY), such as a high-rate PHY (HRP). In oneembodiment, for example, the HRP supports multi-Gb/s throughput at adistance of approximately 10 meters through adaptive antenna technology.Because of this, the antenna pattern used for the HRP is highlydirectional. The HRP is optimized for the delivery of uncompressedhigh-definition video, although other data can be communicated using theHRP. To support multiple video resolutions, the HRP has more than onedata rate defined. The HRP carries isochronous data such as audio andvideo, asynchronous data, MAC commands, antenna beam forminginformation, and higher layer control data for A/V devices. It may beappreciated that the use of HRP and LRP are for WirelessHD devices, andother types of PHYs may be used for other types of devices. With respectto the NGmS protocol, for example, the high rate PHY may be referred toas the OFDM PHY or the SC PHY depending on the modulation type, whilethe low rate PHY is called a CONTROL PHY or a MCS of the SC PHY. In thelatter case, the low rate transmissions will be based on wide bandwidthwith significant processing gain that renders the transmission morerobust. Other types of high rate and low rate PHYs may be used fordifferent types of devices, and the embodiments are not limited in thiscontext.

In various embodiments, the nodes 102, 104 may also communicate using alow-rate PHY (LRP). The LRP is a multi-Mb/s bidirectional link that alsoprovides a relatively short range (e.g., 10 meters). One or more datarates are defined for the LRP, with the lower data rates having nearomni-directional coverage while the highest data rates are directional,although this is not necessarily binding. For example, some arrangementsmay use higher data rates of LRP in almost-omni directionaltransmissions. Because the LRP has near omni-directional modes, it canbe used for both unicast and broadcast connections. Furthermore, becauseall stations support the LRP, it can be used for station-to-stationlinks for WirelessHD devices, although this may not be possible for NGmSdevices. The LRP supports multiple data rates, including directionalmodes, and is used to carry low-rate isochronous data such as audio,low-rate asynchronous data, MAC commands including the beacon,acknowledgements for HRP packets, antenna beam forming information,capabilities information, and higher layer control data for A/V devices.

In some cases (not all) the HRP and LRP may operate in overlappingfrequency bands and so they are coordinated by the MAC. The media accessscheme may include a time division multiple access (TDMA) format, afrequency division multiple access (FDMA) format, a TDMA/FDMA format, acode division multiple access (CDMA), a wide-band CDMA (WCDMA) format,an orthogonal frequency division multiple access (OFDMA) format, and soforth. The embodiments are not limited in this context.

The WVAN typically supports two types of devices. In one embodiment, forexample, a WVAN may support a coordinator and a station. The coordinatorcontrols the timing in the piconet, keeps track of the members of theWVAN, is able to transmit and receive using the LRP, may be able totransmit data using the HRP, and may be able to receive data using theHRP. A station is able to transmit and receive using the LRP, mayinitiate stream connections, may be able to transmit data using the HRP,and may be able to receive data using the HRP. A station may be capableof acting as a coordinator in the WVAN. Such a station is referred to asbeing coordinator capable.

In addition to the two MAC personalities of coordinator and station,each device in a WirelessHD WVAN will have one of four different PHYcapabilities as shown in Table 1 as follows:

TABLE 1 PHY Description HR0 A device that is not able to either receiveor transmit using the HRP HRRX A device that is able to receive in theHRP, but is not able to transmit using the HRP HRTX A device that isable to transmit in the HRP, but is not able to receive using the HRPHRTR A device that is able to both transmit and receive using the HRPAll compliant WirelessHD devices are able to transmit and receive usingthe LRP. Both the HRP and LRP may provide multiple data rates, asspecified in the WirelessHD Specification.

In various embodiments, the transmitter node 102 and the receiver nodes104-1-n may be arranged to communicate various types of mediainformation in multiple communication frames. The various types of mediainformation may include image information, audio information, videoinformation, AV information, and/or other data provided from the mediasource 108. In various embodiments, the information may be associatedwith one or more images, image files, image groups, pictures, digitalphotographs, music file, sound files, voice information, videos, videoclips, video files, video sequences, video feeds, video streams, movies,broadcast programming, television signals, web pages, user interfaces,graphics, textual information (e.g., encryption keys, serial numbers,e-mail messages, text messages, instant messages, contact lists,telephone numbers, task lists, calendar entries, hyperlinks), numericalinformation, alphanumeric information, character symbols, and so forth.The information also may include command information, controlinformation, routing information, processing information, system fileinformation, system library information, software (e.g., operatingsystem software, file system software, application software, gamesoftware), firmware, an application programming interface (API), aprogram, an applet, a subroutine, an instruction set, an instruction,computing code, logic, words, values, symbols, and so forth.

The transmitter node 102 may be arranged to receive media content from amedia source node 110 to be unicast and/or multicast to one or more ofthe receiver nodes 104-1-n. In various embodiments, the transmitter node102 may be arranged to receive media content from the source node 110.The media source node 110 generally may comprise any media sourcecapable of delivering static or dynamic media content to the transmitternode 102. In one embodiment, for example, the media source node 110 maycomprise a multimedia server arranged to provide broadcast or streamingmedia content to the transmitter node 102. In some implementations, themedia source node 110 may form part of a media distribution system (DS)or broadcast system such as an over-the-air (OTA) broadcast system, aradio broadcast system, a television broadcast system, a satellitebroadcast system, and so forth. In some implementations, the mediasource node 110 may be arranged to deliver media content pre-recordedand stored in various formats for use by a device such as a DigitalVersatile Disk (DVD) device, a Video Home System (VHS) device, a digitalVHS device, a digital camera, video camera, a portable media player, agaming device, and so forth.

As shown in the embodiment of FIG. 1, for example, the transmitter node102 may be coupled to the media source node 110 through a communicationmedium 112. The communication medium 112 generally may comprise anymedium capable of carrying information signals such as a wiredcommunication link, wireless communication link, or a combination ofboth, as desired for a given implementation. In various embodiments, thecommunication medium 112 may comprise a wired communication linkimplemented as a wired Ethernet and/or P2P connection, for example. Insuch embodiments, information may be communicated over the communicationmedium 112 in accordance with the information IEEE 802.3, and thetransmitter node 102 may receive media content from the media sourcenode 110 substantially loss-free.

Although some embodiments may be described with the communication medium112 implemented as a wired Ethernet and/or P2P connection for purposesof illustration, and not limitation, it can be appreciated that theembodiments are not limited in this context. For example, thecommunication medium 112 between the transmitter node 102 and the sourcenode 110 may comprise various types of wired and/or wirelesscommunication media and, in some cases, may traverse one or morenetworks between such devices.

The transmitter node 102 may be arranged to buffer media content and toparse or fragment the media content into communication frames forunicast or multicast transmission to the receiver nodes 104-1-n. In someimplementations, the transmitter node 102 may be arranged to parse orfragment the received media content as it is read into a buffer. In someembodiments, the media content provided to the transmitter node 102 maybe delivered as one or more media frames. Each media frame may comprisea discrete data set having a fixed or varying length, and may berepresented in terms of bits or bytes such as 16 kilobytes (kB), forexample. It can be appreciated that the described embodiments areapplicable to various types of communication content or formats, such asframes, packets, fragments, cells, units, and so forth.

In various embodiments, the transmitter node 102 may be arranged tocreate a sequence of media frames to be broadcast over one or more ofthe wireless communication links 108-1-n. Each media frame may comprisea discrete data set having fixed or varying lengths, and may berepresented in terms of bits or bytes. While multicasting, each mediaframe may contain a destination address comprising a group addresscorresponding to multiple intended recipients, such as receiver nodes104-1-n. In some embodiments, the destination address may refer to allreceiver nodes 104-1-n within the wireless network 106.

FIG. 2 illustrates a block diagram of one embodiment of a wirelessnetwork 200. For ease of illustration, and not limitation, the wirelessnetwork 200 depicts a limited number of nodes by way of example. It canbe appreciated that more nodes may be employed for a givenimplementation.

As shown, the wireless network 200 may comprise a wireless device 202coupled to a wireless device 204. In various embodiments, the wirelesscommunications system 200 may comprise or be implemented by one or moreelements of the communications system 100 of FIG. 1, such as wirelessnetwork 100, transmitter node 102, and receiver nodes 104-1-n. Theembodiments are not limited in this context.

In one embodiment, for example, the wireless device 202 and the wirelessdevice 204 may be implemented as WirelessHD compliant devices, and thewireless network 200 may be implemented as a WVAN network. In such anembodiment, the wireless network 200 may communicate information inaccordance with the WirelessHD Specification and associated techniques,and the wireless device 202 may comprise a WirelessHD compliant devicecommunicatively coupled to the wireless device 204 comprising anotherWirelessHD compliant device. In various implementations, the wirelessnetwork 200 may support a unicast and/or multicast communicationenvironment for distributing media content by unicasting and/ormulticasting from the wireless device 202 to the wireless device 204.Typically, the wireless devices 202, 204 will utilize unicast ormulticast techniques based upon the type of channel being used. Forexample, the wireless devices 202, 204 will utilize unicast techniqueswhen using a HRP channel, and multicast techniques when using a LRPchannel. The embodiments are not limited in this context.

In one embodiment, for example, the wireless devices 202, 204 each mayinclude the capability to establish one or more wireless communicationschannels 206 using respective transceivers 205, 205 a coupled torespective antenna control modules 208, 208 a coupled to respectivephased antenna arrays 210, 210 a. In various embodiments, thecommunications channel 206 may be implemented at the MAC layer of thecommunication protocol stack within a transceiver and/or wirelesscommunication chipset of a wireless device.

FIG. 3 illustrates one embodiment of wireless system 300 suitable forperforming analog beam forming. The wireless system 300 may beimplemented for the nodes 102, 104-1-n as described with reference toFIG. 1, and/or the wireless nodes 202, 204 as described with referenceto FIG. 2.

In the illustrated embodiment shown in FIG. 3, the wireless system 300may comprise a more detailed diagram for a pair of phased antenna arrays210, 210 a implemented for respective wireless devices 202, 204. Thephased antenna arrays 210, 210 a may be communicatively coupled to therespective antenna control modules 208, 208 a. The phased antenna array210 may comprise a transmitter antenna array 310 and a receiver antennaarray 320. The phased antenna array 210 a may comprise a transmitterantenna array 330 and a receiver antenna array 340. Although the antennaarrays 310, 320 and the antenna arrays 330, 340 may be illustrated aseparate antenna arrays, it may be appreciated that each may beimplemented using a single antenna array using different transmit andreceive coefficients, vectors or other suitable antenna parameters.

The transmitter antenna arrays 310, 330 may comprise respective poweramplifiers 312-1-a and power amplifiers 332-1-f each coupled torespective phase shifters 314-1-b and phase shifters 334-1-g. The phaseshifters 314-1-b and phase shifters 334-1-g may each be coupled torespective antennas 316-1-c and antennas 336-1-h. The receiver antennaarrays 320, 240 may comprise respective antennas 326-1-d and antennas346-1-i each coupled to respective phase shifters 324-1-e and phaseshifters 344-1-j. The phase shifters 324-1-e and phase shifters 344-1-jmay each be coupled to respective low noise amplifiers (LNA) 322-1-r andLNA 342-1-s, which are in turn each coupled to respective combiners 346,348. It may be appreciated that the transmitter and receiver chains canshare phase shifters and/or amplifiers as desired for a givenimplementation. The embodiments are not limited in this context.

The wireless devices 202, 204 may use the respective phased antennaarrays 210, 210 a to communicate control information and mediainformation over a wireless shared media 350. The transmitter antennaarray 310 and the receiver antenna array 340 of the respective wirelessdevices 202, 204 may communicate information using an HRP channel 352-1and/or a LRP channel 354-1. The transmitter antenna array 330 and thereceiver antenna array 320 of the respective wireless devices 204, 202may communicate information using an HRP channel 352-2 and/or a LRPchannel 354-2. In one embodiment, the HRP channels 352-1, 352-2 may beimplemented as directional channels operating at higher rate datacommunication speeds, and the LRP channels 354-1, 354-2 may beimplemented as omni-directional channels operating at lower rate datacommunications speeds.

The antenna control modules 208, 208 a may use the respectivetransceivers 205, 205 a and respective phased antenna arrays 210, 210 ato perform beam forming operations. The beam forming operations mayinclude explicit feedback beam forming, which supports all types ofWirelessHD compliant devices, such as HR0, HRRX, HRTX and HRTR. There isno requirement that the transmitter and the receiver for a station arethe same and no calibration is required. The beam forming operations mayalso include implicit feedback beam forming, which is typically usedwhen both the source and destination are HRTR capable.

In order to provide data rates on the order of Gbps at approximately 10meters for 60 GHz mmWave operations, the phased antenna arrays 210, 210a are implemented as high gain antenna networks in the 60 GHz frequencyband. The phased antenna arrays 210, 210 a can create beams that can besteered around obstacles to find a best path between the wirelessdevices 202, 204. The antenna control modules 208, 208 a may cooperateto implement an enhanced bidirectional beam forming protocol suitablefor beam search and beam tracking operations. Beam search is a techniqueof estimating transmitter and receiver antenna-array weight vectors(AWVs) that result in a desired beam with an acceptable level of gain orSNR over the HRP channels 352-1, 352-2. Beam tracking is a technique oftracking transmitter and receivers AWVs that correspond to an existingbeam over time due to small perturbations of the HRP channels 352-1,352-2. While beam search is typically a stand-alone technique using adedicated time interval, beam tracking takes place during data transferand is appended to existing HRP packets and corresponding ACK packets.

FIG. 4 illustrates one embodiment of a state diagram 400. The statediagram 400 illustrates state transitions for adaptive beam formingusing the phased antenna arrays 210, 210 a. In the illustratedembodiment shown in FIG. 4, the wireless device 202 may be in an idlestate 402, and detect a peer device (e.g., wireless device 204) withincommunication range of the wireless device 202. The wireless device 202may exit the idle state 402, and enter a beam formation state 404. Thewireless device 202 may initiate beam formation operations using aniterative training scheme to form a pair of communications channels HRP352-1, 352-2 between the wireless devices 202, 204. For example, theantenna control module 208 for the wireless device 202 may be arrangedto communicate training signals and feedback information with thewireless device 204 via the transceiver 205 and phased antenna array210. The information is communicated using exclusively the HRP channels352-1, 352-2, while reducing or eliminating the need to use the LRPchannels 354-1, 354-2. This reduces training time for the devices. Theantenna control module 208 iteratively determines AWVs for a directionaltransmit beam pattern for the phased antenna array 210 using feedbackinformation from the wireless device 204. Once trained the wirelessdevices 202, 204 may exit the beam formation state 404, and enter a datatransfer state 406 to use the HRP channels 352-1, 352-2 forbidirectional high rate data communications.

FIG. 5 illustrates one embodiment of iterative training scheme for awireless system 500. Since the path loss in the 60 GHz frequency band isvery high and the efficiency of CMOS power amplifiers at 60 GHz is low,directional transmission is needed to achieve the desired 10 metercoverage. The array gain from transmit and receive beam formingoperations is needed to acquire the desired SNR for reliable datacommunications. Currently, there are several different beam formingprotocols to acquire directional transmissions. The first beam formingprotocol uses the sectored antenna approach, which switches amongseveral preformed beams. The second beam forming protocol uses phasedantenna arrays where transmit and receive beams are formed by changingthe phases of the input and output signals of each antenna element, asdescribed with reference to FIG. 3.

The second beam forming protocol uses an iterative training approach. Aniterative training process utilizes training sequences and feedback insuccessive iterations in order to train transmitters or receivers. Theiterative training approach provides the advantage of distributingtransmit power to multiple power amplifiers, and the beam can beadaptively steered. It is worthy to note that this discussion is limitedto only a single data stream for purposes of clarity, although someembodiments may be implemented for multiple data streams as well. Abrief overview of iterative training is provided below to betterillustrate and describe the operations and benefits of the enhancedbidirectional beam forming protocol.

In one embodiment, the desired beam forming weights at the receiver (Rx)504 and transmitter (Tx) 502, denoted by vectors u and v, maximize thegain of the beamformed channel as shown in Equation (1) as follows:

$\begin{matrix}{( {u,v} ) = {\underset{{\hat{u}} = {{\hat{v}} = 1}}{\arg\;\max}{{{\hat{u}}^{H}H\;\hat{v}}}}} & (1)\end{matrix}$where H is the effective channel matrix between transmitter 502 andreceiver 504; û^(H)H{circumflex over (v)} is the beam formed scalarchannel for beam forming weights û and {circumflex over (v)}; and u andv are the normalized beam forming vectors at the receiver 504 andtransmitter 502 respectively. The effective channel matrix incorporatesthe effects of the transmit/receive weighting matrixes and the wirelesschannel, and it is the product of the transmit weighting matrix B_(t),wireless channel H_(w), the receive weighting matrix B_(r) e.g.,H=B_(r)H_(w)B_(t). The weight entries on the i-th row of B_(r) form thei-th effective receive antenna and similarly the weight entries on thei-th column of B_(t) form the i-th effective transmit antenna. The entryon the i-th row and j-th column of H is the channel response between thei-th effective receive antenna and the j-th effective transmit antenna.If H is known, then u and v can be computed using the singular valuedecomposition (SVD) of H. However, H is usually unknown at bothtransmitter 502 and receiver 504 for 60 GHz systems. Consequently,iterative training is used as an efficient scheme to obtain u and v, andwhich does not require costly training to learn about the whole H.

Beam forming is needed before the transmission of the data packet. Incurrent protocols and for a P2P scheduled training, and for systemswithout RF transceiver chain calibration, the beam forming weights ofthe phased antenna arrays are gradually refined during the beamrefinement phase that consumes a significant overhead of about 400microseconds (μs), for example. It is desirable to reduce the trainingoverhead as much as possible for high network throughput. In the stateof the art, iterative training is the scheme employed for the beamrefinement because of its superior performance. It is iterative and eachiteration has two steps, e.g., the training of maximum ratio combining(MRC) weights and the training of the maximum ratio transmission (MRT)weights, as shown in FIG. 5 and Equation (2) as follows.Step 1: u(i)=norm(Hv(i))Step 2: v(i+1)=norm(H ^(H) u(i))  (2)where

${{norm}(x)} = \frac{x}{x}$normalizes the magnitude of the beam forming vector. For clarity andsimplicity, the noise term is not evaluated. At the i-th iteration, thetransmitter 502 has the transmit beam forming vector v(i), which comesfrom the feedback from the receiver 504.

In the first step in Equation (2), the transmitter 502 sends trainingsymbols to the receiver 504 using v(i), and the receiver 504 estimatesthe receive beam forming weights that maximize the received signalstrength for the transmit vector v(i) as follows. The receiver measuresthe response on each effective receive antenna respectively, and themeasured responses form the vector Hv(i). The receive beam formingvector maximizing the received signal (e.g., the MRC vector), is shownin Equation (3) as follows:u(i)=norm(Hv(i))  (3)

In the second step in Equation (2), the transmitter 502 sends trainingsymbols through each effective transmit antenna respectively and thereceiver 504 estimates the transmit beam forming weights that maximizethe received signal strength for the receive vector u(i) as follows. Thereceiver uses u(i) as the receive vector and measures the beam formedchannel response for each effective transmit antenna in H respectively.The measured channel responses form the vector u^(H)(i)H. The transmitbeam forming vector maximizing the received signal (e.g., the MRTvector), is shown in Equation (4) as follows:v ^(H)(i+1)=norm(u ^(H)(i)H) or v(i+1)=norm(H ^(H) u(i))  (4)The value for v(i+1) is fed back to the transmitter 502 for the (i+1)-thiteration. The values for u(i) and v(i) gradually converges to the idealu and v as each iteration completes.

Iterative training is currently used by certain conventional beamforming protocols, such as those currently implemented by the WirelessHDSpecification. The conventional beam forming protocol utilized by theWirelessHD Specification, however, introduces a significant amount oftraining overhead and link latency. It is also designed for training alink in one direction at a time, which may be suitable to digitaltelevision sets that are designed to operate mainly as receivers andless as transmitters. A PC environment is different, however, and focusis placed on both transmitting and receiving operations. The enhancedbidirectional beam forming protocol reduces link latency for trainingbidirectional links, and is described in further detail with referenceto FIG. 6.

FIG. 6A illustrates one embodiment of a message flow 600. The messageflow 600 illustrates a message flow for an enhanced bidirectional beamforming protocol that reduces latency introduced by an iterativetraining scheme by using only HRP channels 352-1, 352-2, while reducingor eliminating the need to use the LRP channels 354-1, 354-2. Forpurposes of illustration and not limitation, the wireless device 202 mayrepresent a piconet controller (PNC) or coordinator, and the wirelessdevice 204 may represent a wireless station (STA). In one embodiment,the message flow 600 may be applicable for WirelessHD devices, althoughthe embodiments are not limited in this respect.

In the illustrated embodiments shown in FIG. 6A, the wireless device 202exits the idle state 402 and enters the beam forming state 404. Thewireless device 202 may optionally transmit timing acquisition andoptimal delay selection sequences to the wireless device 204. Theantenna control module 208 of the wireless device 202 cooperates withthe antenna control module 208 a of the wireless device 204 to implementan iterative training scheme using an enhanced bidirectional beamforming protocol. The iterative training scheme may use any number ofiterations 602-1-m as desired for a given implementation.

During a first iterative training 602-1, the antenna control module 208uses the transceiver 205 and the phased antenna array 510 of thewireless device 202 to send training signals, such as training signals613, from the wireless device 202 to the wireless device 204 over adownlink (DL) HRP channel 352-1. In a typical scenario, multipletraining signals are transmitted, while the wireless device 202 changesits antenna weights at proper times (e.g., at the beginning of everytraining signal). For example, the antenna control module 208 sendsreceiver (Rx) training signals 613 from the wireless device 202 to thewireless device 204 over the DL HRP channel 352-1 to allow the wirelessdevice 204 to deduce the MRC weights and form a directional receive beampattern for a phased antenna array 210 a of the wireless device 204. Theantenna control module 208 sends transmitter (Tx) training signals 614from the wireless device 202 to the wireless device 204 over the DL HRPchannel 352-1 to allow the device 204 to measure characteristics of itsreceived signal. These characteristics are later fed back from device204 to device 202 using message 617 to allow wireless device 202 todeduce its MRT weights so that a directional transmit beam pattern forthe phased antenna array 210 of the wireless device 202 can be formed.

In a conventional beam forming protocol, the antenna control module 208may wait to receive feedback information from the wireless device 204over the LRP channel 354-1. In the enhanced bidirectional beam formingprotocols, however, the feedback information from the wireless device204 is delayed until a directional receive beam pattern for the phasedantenna array 210 of the wireless device 202 as been formed or partiallyformed, thereby allowing the wireless device 202 to receive the feedbackinformation from the wireless device 204 over an uplink (UL) HRP channel352-2. The UL HRP channel 352-2 operates at a much higher data rate thanthe LRP channel 354-1, and therefore using the UL HRP channel 352-2 forthe feedback information reduces training overhead and latency.

Referring again to the message flow 600, the antenna control module 208a uses the transceiver 205 a and the phased antenna array 210 a of thewireless device 204 to send training signals or sequences to thewireless device 202 over the UL HRP channel 352-2. For example, theantenna control module 208 a sends training signals 615 to the wirelessdevice 202 over the UL HRP channel 352-2 to deduce the MRC weights andform a directional receive beam pattern for the phased antenna array 210of the wireless device 202. The antenna control module 208 a also sendstraining signals 616 to the wireless device 202 over the UL HRP channel352-2 to allow the wireless device 202 to measure characteristics of itsreceived signal. These characteristics are later fed back from device202 to device 204 using message 618 to allow wireless device 204 todeduce its MRT weights so that a directional transmit beam pattern forthe phased antenna array 210 a of the wireless device 204 can be formed.

Once the phased antenna array 210 of the wireless device 202 has a fullyor partially formed directional receive beam pattern using the weights(e.g., MRC weights) obtained at arrow 615, the wireless device 204 maysend feedback information to the wireless device 202 over the UL HRPchannel 352-2, which is received using the directional receive beampattern for the phased antenna array 210 of the wireless device 202, asindicated by the arrow 617. The phased antenna array 210 a may use thesame transmit beam forming vector as used when previously sending the ULPNC Rx vector training (PNC MRC weights) (arrow 615). This provides thewireless device 202 with receive gain that may not have been availableprior to stage 615 or earlier.

The antenna control module 208 may determine AWVs for the directionaltransmit beam pattern for the phased antenna array 210 of the wirelessdevice 202 using the feedback information from the wireless device 204.The first iteration 602-1 may then be completed by having the wirelessdevice 202 send feedback information to the wireless device 204 over theDL HRP channel 352-1 using a directional transmit beam pattern obtainedfrom recently received feedback information (arrow 617) for the phasedantenna array 210 of the wireless device 202. The phased antenna array210 a of the wireless device 204 may use the directional receive beampattern formed when receiving the DL STA Rx vector training (STA MRCweights) at arrow 613 to receive the feedback information. The antennacontrol module 208 a may then use the feedback information indetermining AWVs for the directional transmit beam pattern for thephased antenna array 210 a of the wireless device 204 using the feedbackinformation from the wireless device 202.

The wireless devices 202, 204 may continue with the next iterativetrainings 602-2-m performing similar beam forming or beam refinementoperations as used with the first iterative training 602-1. For example,for iterative training 602-2 the operations indicated by arrows 619through 624 are similar to those operations performed as indicated byarrows 613 through 618. Each iterative training 602-1-m providessuccessively more accurate AWVs for the HRP channels 352-1, 352-2. Thisprocess continues until a terminating condition is reached, such asreaching a determined SNR for data communications, reaching a determinednumber of iterations (e.g., three iterations), or until both ends of thelink request termination of the training process. At this point, the HRPchannels 352-1, 352-2 may be used for bidirectional high rate datacommunications.

It is worthy to note that the feedback information provided at arrow 617may optionally be moved back and provided during stage 616. This may addsynchronization overhead, however, because of the transmit/receiveswitching.

FIG. 6B illustrates one embodiment of a message flow 650. The messageflow 650 illustrates a message flow for an enhanced bidirectional beamforming protocol that reduces latency introduced by an iterativetraining scheme by using predominantly HRP channels 352-1, 352-2, whilereducing or eliminating the need to use the LRP channels 354-1, 354-2.For purposes of illustration and not limitation, the wireless device 202may represent a piconet controller (PNC) or coordinator, and thewireless device 204 may represent a wireless station (STA). In oneembodiment, the message flow 650 may be applicable for NGmS devices,although the embodiments are not limited in this respect.

In the illustrated embodiments shown in FIG. 6A, the message flow 650illustrates a message flow suitable for an enhanced bidirectional beamforming protocol implemented for a NGmS network, protocol or devices.The NGmS protocol, for example, may contain DL RX training, DL feedbackand DL TX training, followed by UL RX training, UL feedback and UL TXtraining, where the DL feedback is feedback sent over a downlinkcorresponding to UL TX training that was previously transmitted.

The message flow 650 of FIG. 6B is similar to the message flow 600described with reference to FIG. 6A, with a different sequencing for thetraining signals and messages. As shown in the message flow 650, signalsand/or messages 613 to 618 are reordered in the following sequence: 613,618, 614, 615, 617 and 616. It may be appreciated that this sequencingprovides the following characteristics: (1) all arrows in the samedirection may be grouped together to form a single packet; and (2) in agroup there is RX training, feedback information and then TX training.Unlike message flow 600, where the feedback information can correspondto current iteration training, the message flow 650 corresponds toprevious iteration training. The embodiments are not limited in thiscontext.

FIG. 7 illustrates one embodiment of a graph 700 for beam forming gain.The graph 700 provides a number of iterations on a x-axis and a combinedoutput (dB) on a y-axis. As a result of the enhanced bidirectional beamforming protocol, the feedback at arrow 618 is sent with approximately15-25 dB beam forming gain (depending on which iteration) due toperforming both transmit and receive beam forming. For example,approximately 15 dB gain may be achieved in the first iteration 602-1,and 5-6 dB additional gain may be achieved in the second iteration602-2. After the second iteration 602-2, progressively smaller gains arerealized by each successive iteration (e.g., 602-3 through 602-9). TheseSNR improvements enable much faster feedback for beam forming operationswithout calibration. These results correspond to 32 or 36 antennaelements on both sides.

FIG. 8 illustrates one embodiment of a message flow 800. The messageflow 800 illustrates an alternative message flow for an enhancedbidirectional beam forming protocol that reduces latency introduced byan iterative training scheme by using the HRP channels 352-1, 352-2,while reducing or limiting the need to use the LRP channels 354-1,354-2. For purposes of illustration and not limitation, the wirelessdevice 202 may represent a piconet controller (PNC) or coordinator, andthe wireless device 204 may represent a wireless station (STA).

Similar to the message flow 600, the message flow 800 attempts tocoordinate transmit and receive beam forming operations to allowfeedback information to be provided over the HRP channels 352-1, 352-2.The wireless device 202 exits the idle state 402 and enters the beamforming state 404. The wireless device 202 utilizes the message flow 800to initiate bidirectional beam formation operations using an iterativetraining scheme to form a pair of communications channels for a WPAN orWVAN. The message flow 800 interleaves transmit and receive beam formingoperations to allow use of partially trained links to communicatefeedback information at a higher data rate. More particularly, themessage flow 800 interleaves transmit and receive beam formingoperations for the wireless devices 202, 204 to allow feedbackinformation received by the wireless device 202 from the wireless device204 to be communicated over the HRP channels 352-1, 352-2. This reducesthe need to use the LRP channels 354-1, 354-2 during beam formingoperations.

In the illustrated embodiment shown in FIG. 8, the message flow 800begins with optional timing acquisition and optimal delay selectionoperations. During a first iterative training 802-1, the antenna controlmodule 208 sends transmitter (Tx) training signals 813 from the wirelessdevice 202 to the wireless device 204 over the DL HRP channel 352-1 toallow the device 204 to measure characteristics of its received signal.The wireless device 202 receives feedback information 814 from thewireless device 204 over the UL LRP 354-2 to deduce its MRT weights. Theantenna control module 208 of the wireless device 202 determines AWVsfor the directional transmit beam pattern for the phased antenna array210 of the wireless device 202 using the feedback information 814 fromthe wireless device 204.

The wireless device 202 then sends Rx training signals (STA MRC weights)to the wireless device 204 over the DL HRP 352-1 to allow the wirelessdevice 204 to deduce and form a directional receive beam pattern for thephased antenna array 210 a of the wireless device 204, as indicated byarrow 815. The wireless device 202 receives Tx training signals (STA MRTweights) from the wireless device 204 over the UL HRP 352-2 to form adirectional transmit beam pattern for the phased antenna array 210 a ofthe wireless device 204, as indicated by arrow 816.

The antenna control module 208 uses the transceiver 205 and the phasedantenna array 510 of the wireless device 202 to send training signals815 from the wireless device 202 to the wireless device 204 over adownlink DL HRP channel 352-1 to allow the wireless device 204 to deducethe MRC weights and form a directional receive beam pattern for a phasedantenna array 210 a of the wireless device 204. The antenna controlmodule 208 a also sends training signals 816 to the wireless device 202over the UL HRP channel 352-2 to allow the wireless device 202 tomeasure characteristics of its received signal.

The wireless device 202 sends feedback information 817 to the wirelessdevice 204 over the DL HRP 352-1 using a directional transmit beampattern for the phased antenna array 210 of the wireless device 202. Thefeedback information 817 is carried using a partially trained linkobtained in the recent half-iteration. As a result, the feedbackinformation 817 is much more robust and efficient than using only the DLLRP channel 354-1. The wireless device 204 uses the feedback informationto determine AWVs for the directional transmit beam pattern for thephased antenna array 210 a of the wireless device 204 using the feedbackinformation 817 from the wireless device 202.

To complete the first iterative training 802-1, the wireless device 202receives training signals 818 by the wireless device 202 from thewireless device 204 over the UL HRP 352-2 to deduce MRC weights and forma directional receive beam pattern for the phased antenna array 210 ofthe wireless device 202.

The wireless devices 202, 204 may continue with the next iterativetrainings 802-2-k performing similar beam forming or beam refinementoperations as used with the first iterative training 802-1. For example,the wireless device 202 may receive additional feedback information fromthe wireless device 204 over the UL HRP 352-2 using the directionalreceive beam pattern for the phased antenna array 210 of the wirelessdevice 202 during the second iterative training 802-2. The antennacontrol module 210 may determine AWVs for the directional transmit beampattern for the phased antenna array 210 of the wireless device 202using the additional feedback information from the wireless device 204.Each iterative training 802-1-k provides successively more accurate AWVsfor the HRP channels 352-1, 352-2. This process continues until aterminating condition is reached, such as reaching a determined SNR fordata communications or reaching a determined number of iterations (e.g.,three iterations). At this point, the HRP channels 352-1, 352-2 may beused for bidirectional high rate data communications.

The enhanced bidirectional beam forming protocol utilizes partiallytrained links to provide a higher data rate for the feedback informationduring the feedback stages. In the WirelessHD Specification, by way ofcontrast, feedback stages after the first one are done using“directional” mode, which is a selected antenna pattern. Withnon-calibrated antennas, a random antenna pattern may yield less than 0dBi in certain directions. The directional mode is expected to be around0 dBi as it is the best among few random choices. An additionaladvantage of the enhanced bidirectional beam forming protocol is thatthe beamformer need not transfer the selected antenna pattern for thedirectional mode to the beamformee, since the next time feedback isalready going to be over a beamformed link, which is properly trained.

FIG. 9 illustrates one embodiment of a phased array antenna 900. Thephased array antenna 900 may be representative of, for example, thephased array antennas 210, 210 a. In the illustrated embodiment shown inFIG. 9, the phased array antenna 900 may comprise multiple antennaelements 902-1-p.

In some embodiments, the enhanced bidirectional beam forming protocolmay train a subset of antenna elements 902-1-p from the phased arrayantenna 900. The first few iterations of beam forming operations may beof reduced time and quality. When the phased antenna array 900 isimplemented by the wireless device 202, and has 36 antenna elements902-1 through 902-36, then the antenna control module 208 can couplesome of the antenna elements 902-1 through 902-36 together and generatetraining for fewer overall antenna elements 902-1 through 902-36. Thisshortens the time of the training in the first iterative trainings andmay still capture some of the expected antenna gain. An example for suchcoupling is depicted in FIG. 9, where four (4) antenna elements 902-5,902-10, 902-12 and 902-17 marked in cross-hatchings, for example, arealways phase shifted by the same amount, such as 90 degrees, 180 degreesor 270 degrees. This results in essentially eight (8) to nine (9)antenna elements made from the 6×6 phased antenna array 900.

By way of example, referring again to the exemplary message flows 600,800, the wireless device 202 may send Tx training signals to thewireless device 204 over the DL HRP 352-1 to form a directional transmitbeam pattern for a subset of antenna elements 902-1-p of the phasedantenna array 210 of the wireless device 202.

Additionally or alternatively, the wireless devices 202, 204 mayexchange additional information during the enhanced bidirectional beamforming protocol that may accelerate beam forming operations. Forexample, similar to the way that the WirelessHD Specification uses toidentify the proper antenna pattern index for the directional mode, theenhanced bidirectional beam forming protocol can add additionalinformation types to certain stages of beam forming operations, such aneeded modulation and coding scheme (MCS) for the wireless devices 202,204. An information field of defined length (e.g., 3 bits) may be usedto communicate the MCS information. The MCS information may becommunicated, for example, with the transmitter training signals ineither link direction in order to assist in generating the feedbackinformation during the feedback stages. Other types of information otherthan MCS information may be sent during different stages of the enhancedbidirectional beam forming protocol, and the embodiments are not limitedin this context.

In embodiments, the feedback information may correspond to measurementsdone at the receiver and is largely unaware of the antenna patternsapplied by the transmitter. An example of feedback information maycomprise a channel estimation per given delay, among others. In someembodiments, the amount of feedback information may be uniform.Additionally or alternatively, the wireless devices 202, 204 mayexchange increasing amounts of feedback information during the feedbackstages of the enhanced bidirectional beam forming protocol to acceleratebeam forming operations. When the HRP channels 352-1, 352-2 arepartially or fully formed, and the feedback overhead becomes cheaper,then one or both of the wireless devices 202, 204 can increase theamount of feedback information provided over the HRP channels 352-1,352-2 at certain stages and/or iterative trainings so that the overallbeam forming training time is reduced.

Operations for various embodiments may be further described withreference to the following figures and accompanying examples. Some ofthe figures may include a logic flow. It can be appreciated that anillustrated logic flow merely provides one example of how the describedfunctionality may be implemented. Further, a given logic flow does notnecessarily have to be executed in the order presented unless otherwiseindicated. In addition, a logic flow may be implemented by a hardwareelement, a software element executed by a processor, or any combinationthereof. The embodiments are not limited in this context.

FIG. 10 illustrates one embodiment of a logic flow 1000 for selecting achannel pair to form a new wireless network between two or more devices.In various embodiments, the logic flow 1000 may be performed by varioussystems, nodes, and/or modules and may be implemented as hardware,software, and/or any combination thereof, as desired for a given set ofdesign parameters or performance constraints. For example, the logicflow 1000 may be implemented by a logic device (e.g., transmitter node,receiver node) and/or logic comprising instructions, data, and/or codeto be executed by a logic device. For purposes of illustration, and notlimitation, the logic flow 1000 is described with reference to FIG. 1.The embodiments are not limited in this context.

In one embodiment, for example, the logic flow 1000 may initiate beamformation operations using an iterative training scheme to form a pairof communications channels for a wireless network at block 1002. Forexample, the wireless device 202 may initiate beam formation operationsusing an iterative training scheme to form a pair of communicationschannels (352-1, 352-2) for a 60 GHz mmWave WPAN or WVAN. Theembodiments are not limited in this context.

In one embodiment, for example, the logic flow 1000 may communicatetraining signals and feedback information between a first device and asecond device using only high rate channel at block 1004. For example,may communicate training signals and feedback information between thewireless devices 202, 204 using only HRP channels 352-1, 352-2. Theembodiments are not limited in this context.

In one embodiment, for example, the logic flow 1000 may determineantenna-array weight vectors for a directional transmit beam pattern fora phased antenna array of the first device using feedback informationfrom the second device at block 1006. For example, the antenna controlmodule 208 of the wireless device 202 may determine AWVs for adirectional transmit beam pattern for the phased antenna array 210 ofthe wireless device 202 using feedback information from the wirelessdevice 204. The embodiments are not limited in this context.

FIG. 11 illustrates one embodiment of an article of manufacture 1100. Asshown, the article 1100 may comprise a storage medium 1102 to storelogic 1104 for selecting a channel pair to form a new wireless networkbetween two or more devices. For example, logic 1104 may be used toimplement the channel selection module 208, as well as other aspects ofthe transmitter node (102, 202) and/or the receiver nodes (104-1-n,204). In various embodiments, the article 1100 may be implemented byvarious systems, nodes, and/or modules.

The article 1100 and/or machine-readable storage medium 1102 may includeone or more types of computer-readable storage media capable of storingdata, including volatile memory or, non-volatile memory, removable ornon-removable memory, erasable or non-erasable memory, writeable orre-writeable memory, and so forth. Examples of a machine-readablestorage medium may include, without limitation, random-access memory(RAM), dynamic RAM (DRAM), Double-Data-Rate DRAM (DDR-DRAM), synchronousDRAM (SDRAM), static RAM (SRAM), read-only memory (ROM), programmableROM (PROM), erasable programmable ROM (EPROM), electrically erasableprogrammable ROM (EEPROM), Compact Disk ROM (CD-ROM), Compact DiskRecordable (CD-R), Compact Disk Rewriteable (CD-RW), flash memory (e.g.,NOR or NAND flash memory), content addressable memory (CAM), polymermemory (e.g., ferroelectric polymer memory), phase-change memory (e.g.,ovonic memory), ferroelectric memory,silicon-oxide-nitride-oxide-silicon (SONOS) memory, disk (e.g., floppydisk, hard drive, optical disk, magnetic disk, magneto-optical disk), orcard (e.g., magnetic card, optical card), tape, cassette, or any othertype of computer-readable storage media suitable for storinginformation. Moreover, any media involved with downloading ortransferring a computer program from a remote computer to a requestingcomputer carried by data signals embodied in a carrier wave or otherpropagation medium through a communication link (e.g., a modem, radio ornetwork connection) is considered computer-readable storage media.

The article 1100 and/or machine-readable medium 1102 may store logic1104 comprising instructions, data, and/or code that, if executed by amachine, may cause the machine to perform a method and/or operations inaccordance with the described embodiments. Such a machine may include,for example, any suitable processing platform, computing platform,computing device, processing device, computing system, processingsystem, computer, processor, or the like, and may be implemented usingany suitable combination of hardware and/or software.

The logic 1104 may comprise, or be implemented as, software, a softwaremodule, an application, a program, a subroutine, instructions, aninstruction set, computing code, words, values, symbols or combinationthereof. The instructions may include any suitable type of code, such assource code, compiled code, interpreted code, executable code, staticcode, dynamic code, and the like. The instructions may be implementedaccording to a predefined computer language, manner or syntax, forinstructing a processor to perform a certain function. The instructionsmay be implemented using any suitable high-level, low-level,object-oriented, visual, compiled and/or interpreted programminglanguage, such as C, C++, Java, BASIC, Perl, Matlab, Pascal, VisualBASIC, assembly language, machine code, and so forth. The embodimentsare not limited in this context. When implemented the logic 1104 isimplemented as software, the software may be executed by any suitableprocessor and memory unit.

It is worthy to note that although the terms “downlink” and “uplink”channels are used when describing some embodiments, these terms are usedto differentiate between two different channels being used between twodifferent devices. Alternate terms may include a “first” channel and a“second” channel, a “forward” channel and a “reverse” channel, and anyother suitable labels. Any two channels between any two devices may beused with an enhanced bidirectional beam forming protocol as describedherein, and still fall within the scope of the embodiments. Theembodiments are not limited in this context.

It is also worthy to note that the increased gain provided by anenhanced bidirectional beam forming protocol may be realized at anypoint during iterative training operations due to variations in theiterative training operations for different types of protocols (e.g.,WirelessHD, NGmS, and so forth), and flexibility in modifying aparticular implementation for interleaving operations in support ofbidirectional beamforming operations. For example, the increased gainfrom communicating feedback information as described with reference FIG.6B may be realized during the first iteration or second iterationdepending on a particular implementation. The embodiments are notlimited in this context.

Numerous specific details have been set forth herein to provide athorough understanding of the embodiments. It will be understood bythose skilled in the art, however, that the embodiments may be practicedwithout these specific details. In other instances, well-knownoperations, components and circuits have not been described in detail soas not to obscure the embodiments. It can be appreciated that thespecific structural and functional details disclosed herein may berepresentative and do not necessarily limit the scope of theembodiments.

Unless specifically stated otherwise, it may be appreciated that termssuch as “processing,” “computing,” “calculating,” “determining,” or thelike, refer to the action and/or processes of a computer or computingsystem, or similar electronic computing device, that manipulates and/ortransforms data represented as physical quantities (e.g., electronic)within the computing system's registers and/or memories into other datasimilarly represented as physical quantities within the computingsystem's memories, registers or other such information storage,transmission or display devices. The embodiments are not limited in thiscontext.

It is also worthy to note that any reference to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, appearances of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thespecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures or characteristics maybe combined in any suitable manner in one or more embodiments.

While certain features of the embodiments have been illustrated asdescribed herein, many modifications, substitutions, changes andequivalents will now occur to those skilled in the art. It is thereforeto be understood that the appended claims are intended to cover all suchmodifications and changes as fall within the true spirit of theembodiments.

The invention claimed is:
 1. An apparatus, comprising: a phased antennaarray; a transceiver communicatively coupled to the phased antennaarray; and an antenna control module communicatively coupled to thetransceiver and the phased antenna array, the antenna control module toinitiate beam formation operations using an iterative training scheme toform a pair of communications channels for a wireless network whereinthe pair of communication channels includes a high rate physical (HRP)channel and a low rate physical (LRP) channel, receive and send trainingsignals over the HRP channel, and receive and send feedback informationover the HRP channel.
 2. The apparatus of claim 1, comprising: adisplay; a processor; and a memory coupled with the processor.
 3. Theapparatus of claim 1, the formation of the HRP channel comprising:sending training signals to a peer device over the HRP channel;receiving feedback information from the peer device over the LRPchannel; and determining antenna-array weight vectors (AWV) for adirectional transmit beam pattern for a phase antenna array based on thefeedback information.
 4. The apparatus of claim 1, the antenna controlmodule to send transmitting timing acquisition sequences over the HRPchannel.
 5. The apparatus of claim 1, the antenna control module to sendtransmitting delay selection sequences over the HRP channel.
 6. Theapparatus of claim 1, the antenna control module to send transmittertraining signals to a peer device over the HRP channel, the transmittertraining signals for use in forming a directional transmit beam patternfor the phased antenna array.
 7. The apparatus of claim 1, the antennacontrol module to receive receiver training signals from a peer deviceover the HRP to form a directional receive beam pattern for the phasedantenna array.
 8. The apparatus of claim 1, the antenna control moduleto receive transmitter training signals from a peer device over the HRPto form a directional transmit beam pattern for a phased antenna arrayof the peer device.
 9. The apparatus of claim 1, the antenna controlmodule to receive feedback information from a peer device over the LRPchannel using a directional receive beam pattern for the phased antennaarray.
 10. The apparatus of claim 1, the antenna control module to sendfeedback information to a peer device over the LRP channel using adirectional transmit beam pattern for the phased antenna array, thefeedback information for use in determining antenna-array weight vectors(AWV) for a directional transmit beam pattern for a phased antenna arrayof the peer device.
 11. The apparatus claim 1, the antenna controlmodule to continue beam forming operations using multiple iterationsuntil a determined signal-to-noise ratio for data communications isreached or a determined number of iterations is reached.
 12. A methodcomprising: initiating beam formation operations using an iterativetraining scheme to establish a pair of communications channels between afirst device and a second device for a wireless network wherein the pairof communication channels includes a high rate physical (HRP) channeland a low rate physical (LRP) channel; receiving, by the first device,training signals from the second device over the HRP channel; andsending, by the first device, feedback information to the second deviceover the HRP channel.
 13. The method of claim 12, the establishment ofthe HRP channel comprising: sending, by the first device, trainingsignals to the second device over the HRP channel; receiving, by thefirst device, feedback information from the second device over the LRPchannel; and determining antenna-array weight vectors (AWV) for adirectional transmit beam pattern for a phase antenna array based on thefeedback information.
 14. The method of claim 12, the establishment ofthe HRP channel comprising transmitting timing acquisition sequences.15. The method of claim 12, the establishment of the HRP channelcomprising transmitting delay selection sequences.
 16. The method ofclaim 12, comprising sending transmitter training signals from the firstdevice to the second device over the HRP channel to form a directionaltransmit beam pattern for a phased antenna array of the first device.17. The method of claim 12, comprising receiving receiver trainingsignals by the first device from the second device over the HRP channelto form a directional receive beam pattern for a phased antenna array ofthe first device.
 18. The method of claim 12, comprising receivingtransmitter training signals by the first device from the second deviceover the HRP channel to form a directional transmit beam pattern for aphased antenna array of the second device.
 19. The method of claim 12,comprising: receiving feedback information by the first device from thesecond device over the LRP channel using a directional receive beampattern for a phased antenna array of the first device; and determiningantenna-array weight vectors (AWV) for a directional transmit beampattern for a phased antenna array of the first device using thefeedback information from the second device.
 20. The method of claim 12,comprising sending feedback information from the first device to thesecond device over the LRP channel using a directional transmit beampattern for a phased antenna array of the first device, the feedbackinformation for use in determining antenna-array weight vectors (AWV)for a directional transmit beam pattern for a phased antenna array ofthe second device using the feedback information from the first device.21. The method of claim 12, comprising communicating training signalsand feedback information, and determining antenna-array vector weights(AWV) for a directional transmit beam pattern for a phased antenna arrayof the first device, using multiple iterations until a determinedsignal-to-noise ratio for data communications is reached or until adetermined number of iterations is reached.
 22. An article comprising anon-transitory computer-readable storage medium containing a pluralityof instructions that when executed enable a processor to: initiate beamformation operations using an iterative training scheme to establish apair of communications channels for a wireless network wherein the pairof communication channels includes a high rate physical (HRP) channeland a low rate physical (LRP) channel; receive training signals from apeer device over the HRP channel; and send feedback information to thepeer device over the HRP channel.
 23. The article of claim 22, thenon-transitory computer-readable storage medium comprising instructionsthat when executed enable the processor to: send training signals to thepeer device over the HRP channel; receive feedback information from thepeer device over the LRP channel; and determine antenna-array weightvectors (AWV) for a directional transmit beam pattern for a phaseantenna array based on the feedback information.
 24. The article ofclaim 22, the non-transitory computer-readable storage medium comprisinginstructions that when executed enable the processor to transmit timingacquisition sequences to establish the HRP channel.
 25. The article ofclaim 22, the non-transitory computer-readable storage medium comprisinginstructions that when executed enable the processor to transmit delayselection sequences to establish the HRP channel.
 26. The article ofclaim 22, the non-transitory computer-readable storage medium comprisinginstructions that when executed enable the processor to send transmittertraining signals to the peer device over the HRP channel to form adirectional transmit beam pattern for a phased antenna array.
 27. Thearticle of claim 22, the non-transitory computer-readable storage mediumcomprising instructions that when executed enable the processor toreceive receiver training signals from the peer device over the HRPchannel to form a directional receive beam pattern for a phased antennaarray.
 28. The article of claim 22, the non-transitory computer-readablestorage medium comprising instructions that when executed enable theprocessor to receive transmitter training signals from the peer deviceover the HRP channel to form a directional transmit beam pattern for aphased antenna array of the peer device.
 29. The article of claim 22,the non-transitory computer-readable storage medium comprisinginstructions that when executed enable the processor to: receivefeedback information from the peer device over the LRP channel using adirectional receive beam pattern for a phased antenna array; anddetermine antenna-array weight vectors (AWV) for a directional transmitbeam pattern for the phased antenna array using the feedback informationfrom the peer device.
 30. The article of claim 22, the non-transitorycomputer-readable storage medium comprising instructions that whenexecuted enable the processor to send feedback information to the peerdevice over the LRP channel using a directional transmit beam patternfor a phased antenna array, the feedback information for use indetermining antenna-array weight vectors (AWV) for a directionaltransmit beam pattern for a phased antenna array of the peer deviceusing the feedback information.
 31. The article of claim 22, thenon-transitory computer-readable storage medium comprising instructionsthat when executed enable the processor to communicate training signalsand feedback information, and determining antenna-array vector weights(AWV) for the directional transmit beam pattern for a phased antennaarray using multiple iterations until a determined signal-to-noise ratiofor data communications is reached or until a determined number ofiterations is reached.